Method of manufacturing a magneto-resistive device

ABSTRACT

A method is provided for manufacturing a magneto-resistive device. The magneto-resistive device is for reducing the deterioration in the characteristics of the device due to annealing. The magneto-resistive device has a magneto-resistive layer formed on one surface side of a base, and an insulating layer formed of two layers and deposited around the magneto-resistive layer. The layer of the insulating layer closest to the base is made of a metal or semiconductor oxide. This layer extends over end faces of a plurality of layers made of different materials from one another, which make up the magneto-resistive device, and is in contact with the end faces of the plurality of layers with the same materials.

This is a Division of application Ser. No. 10/747,162 filed Dec. 30,2003, now abandoned. The disclosure of the prior application is herebyincorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a magneto-resistive device and a methodof manufacturing the same, and a magnetic head, a head suspensionassembly and a magnetic disk apparatus which use the magneto-resistivedevice.

With the trend to a larger capacity and a smaller size of hard diskdrives (HDD), heads are required to have a higher sensitivity and alarger output. To meet these requirements strenuous efforts have beenmade to improve the characteristics of GMR heads (GiantMagneto-Resistive Head) currently available on the market. On the otherhand, intense development is under way for a tunnel magneto-resistivehead (TMR head) which can be expected to have a resistance changingratio twice or more higher than the GMR head.

Generally, the GMR head differs from the TMR head in the head structuredue to a difference in a direction in which a sense current is fed. Ahead structure adapted to feed a sense current in parallel with a filmsurface, as in a general GMR head, is referred to as a CIP (Current InPlane) structure, while a head structure adapted to feed a sense currentperpendicularly to a film surface, as in the TMR head, is referred to asa CPP (Current Perpendicular to Plane) structure. Since the CPPstructure can use a magnetic shield itself as an electrode, it isessentially free from short-circuiting between the magnetic shield and adevice (defective insulation) which is a serious problem in reducing alead gap in the CIP structure. For this reason, the CPP structure issignificantly advantageous in providing a higher recording density.

Other than the TMR head, also known as a head in CPP structure is, forexample, a CPP-GMR head which has the CPP structure, though a spin valvefilm (including a specular type and dual spin valve type magneticmultilayer films) is used for a magneto-resistive device.

Any type of CPP-based heads has an upper electrode and a lower electrodefor supplying a current to a magneto-resistive layer formed on a base,formed on the top (opposite to the base) and on the bottom (close to thebase) of the magneto-resistive layer, respectively. The CPP-based headcomprises an insulating layer for limiting a current path between theupper electrode and lower electrode is arranged around a main layer (forexample, a tunnel barrier layer in a TMR head) of the magneto-resistivelayer. The limited current path substantially matches an effectiveregion for detecting a magnetic field from a magnetic recording medium.A TMR head is disclosed as an example of the CPP-based head inJP-A-2001-23131 corresponding to U.S. Pat. No. 6,473,257 andJP-A-2001-52316 corresponding to U.S. patent application Publication No.2003/0151859.

In a conventional general CPP-based head as disclosed inJP-A-2001-23131, an insulating layer for limiting a current path betweenan upper electrode and a lower electrode is formed of a single-layerfilm. This insulating layer is generally made of Al2O3 or SiO2.

Generally, for manufacturing a conventional CPP-based head as disclosedin JP-A-2001-23131, constituent layers formed on a substrate, which makeup a magneto-resistive layer, are milled using a resist mask to patternthe constituent layers. Then, the resist mask is used as it is to forman insulating layer of Al2O3 or SiO2 around the constituent layers by alift-off method.

On the other hand, in a conventional TMR head disclosed inJP-A-2001-52316, an insulating layer for limiting a current path betweenan upper electrode and a lower electrode is composed of a firstinsulating layer formed near an end face of a ferromagnetic tunneljunction film (corresponding to a magneto-resistive layer) having atunnel barrier layer as well as a pinned layer and a free layer whichsandwich the tunnel barrier layer, and a second insulating layer whichsurrounds the end face of the ferromagnetic tunnel junction film throughthe first insulating layer. The first insulating layer is made of oxidesof metal materials which constitute the ferromagnetic tunnel junctionfilm pattern formed within the ferromagnetic tunnel junction filmpattern. In other words, the first insulating layer is a layer made ofmetal oxides produced by oxidizing the constituent layers themselves ofthe ferromagnetic tunnel junction film, used as base materials,respectively, and is not a layer disposed on the end face of theferromagnetic tunnel junction film pattern from the outside of theferromagnetic tunnel junction film pattern. Consequently, metal oxidefilms made of different materials from one another are in contact withthe end faces of a plurality of layers made of different materials fromone another, which make up the ferromagnetic tunnel junction film, andthe first insulating layer is composed of a sequence of these metaloxide films made of different materials from one another. The secondinsulating layer is made of an Al oxide, a Si oxide, or the like.

For manufacturing the conventional TMR head disclosed inJP-A-2001-52316, (a) a ferromagnetic tunnel junction film pattern(constituent layers which make up a magneto-resistive layer) formed on asubstrate is milled using a resist mask to pattern the constituentlayers; (b) the end face portions of the constituent layers themselves,used as base materials, are naturally oxidized or oxidized by a plasmaoxidation method or the like to produce the first insulating layer fromthe end faces themselves; and (c) the second insulating layer is formedaround the constituent layers using the resist mask as it is by alift-off method.

According to the conventional TMR head disclosed in JP-A-2001-52316,even if the milling causes milling re-deposits to stick near the ends ofthe constituent layers during the manufacturing, the milling re-depositsare oxidized and included in the first insulating layer which does notprovide a bypass path for a sense current, advantageously preventing areduction in the MR ratio, as described in JP-A-52316.

It should be understood that generally, magnetic heads have not only areproducing device such as a TMR device, a GMR device and the like, butalso a recording device such as an inductive magnetic transducing deviceand the like, so that a composite magnetic head is typically providedfor reproducing and recording magnetic information. During manufacturingof such a composite magnetic head, generally, a reproducing device isformed on a substrate before a recording device is laminated thereon.Then, annealing is performed as a photoresist curing step when a coil isfabricated during the fabrication of the recording device. For example,JP-A-2001-52316 describes that for manufacturing a composite magnetichead which has a recording device laminated on a TMR device, annealingis performed for two hours at 250° C. as a photoresist curing stepduring the fabrication of a coil of the recording device.

The result of a research made by the inventors has revealed that theconventional magnetic heads as disclosed in JP-A-2001-23131 andJP-A-2001-52316 suffer from deteriorated characteristics of the TMRdevices due to the annealing. In this regard, description will be madebelow.

The inventors fabricated a magnetic head similar to that disclosed inJP-A-2001-23131. The fabricated magnetic head had an inductive magnetictransducing device laminated on a TMR device as a recording device.Also, annealing was performed as a photoresist curing step during thefabrication of a coil of the recording device. Further, in the course ofthe fabrication of the magnetic head, the fabricated TMR deviceunderwent the first measurement of the characteristics thereof (theresistance and MR ratio of the TMR device) before the creation of therecording device on the fabricated TMR device. Then, the TMR deviceagain underwent the second measurement of the characteristic thereof(the resistance and MR ratio of THE TMR device) after the recordingdevice had been created.

A comparison of the results of the first measurement with the results ofthe second measurement has revealed that the characteristics of the TMRdevice after the creation of the recording device were significantlydeteriorated as compared with those before the creation of the recordingdevice, contrary to an assumption that the characteristics of the TMRdevice would be the same before and after the creation of the recordingdevice. Specifically, the resistance of the TMR device taken in thesecond measurement was higher than the resistance of the TMR devicetaken in the first measurement, while the MR ratio of the TMR devicetaken in the second measurement was lower than the MR ratio of the TMRdevice taken in the first measurement. The TMR device has a challenge ofreducing the resistance of the device itself because noiseproportionally increases as the resistance of the device is higher.Further, a higher MR ratio is desired because a reduced MR ratio causesa smaller head output.

The results of more detailed experiments made by the inventors haverevealed that the aforementioned deterioration in the characteristics ofthe TMR device (increased resistance and reduced MR ratio) are caused bythe annealing performed for fabricating the recording device.

Magneto-resistive devices such as the TMR device have a variety ofapplications such as a magnetic detector, MRAM (Magnetic Random AccessMemory), and the like, other than magnetic heads, and the annealing issometimes involved in these applications.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a magneto-resistivedevice which can reduce the deterioration in the device characteristicsdue to annealing, and a method of manufacturing the same, as well as amagnetic head, a head suspension assembly, and a magnetic disk apparatuswhich use the magneto-resistive device.

The result of a further research made by the inventors has revealed thatthe deterioration in the characteristics of the TMR device (increasedresistance and reduced MR ratio) due to annealing appears to be causedunder the influence of moisture, oxygen, hydrocarbons (HC), and the likeadsorbed on the end face of the magneto-resistive device when it isexposed to the atmosphere after patterning thereof (or even if themagneto-resistive layer is not exposed to the atmosphere, moisture,oxygen, HC, and the like remaining as impurities in a vacuum chamber canadsorb on the end face of the magneto-resistive layer).

Based on the foregoing, the inventors thought it possible to reduce thedeterioration in the characteristics of the magneto-resistive device dueto the annealing by employing technical means set forth in respectiveaspects of the present invention as described below. The experimentsdescribed later have revealed that the technical means are actuallyeffective.

A magneto-resistive device according to a first aspect of the presentinvention includes a magneto-resistive layer formed on one surface sideof a base, and an insulating layer formed to be in contact with aneffective region effectively involved in detection of magnetism in themagneto-resistive layer without overlapping with the effective region,wherein the insulating layer comprises two or more layers, the layer ofthe insulating layer closest to the base is made of a metal orsemiconductor oxide, and the layer of the insulating layer closest tothe base extends over end faces of a plurality of layers made ofdifferent materials from one another and making up the magneto-resistivelayer, and is in contact with the end faces of the plurality of layerswith the same materials.

When focusing attention only on the fact that the insulating layer mayinclude two layers and that the layer of the insulating layer closest tothe base may be made of a metal oxide in the magneto-resistive deviceaccording to the first aspect, the magneto-resistive device according tothe first aspect is thought to apparently have a structure similar tothe conventional TMR head disclosed in JP-A-2001-52316. This is becausethe layer of the insulating layer closest to the base in the firstaspect corresponds to the first insulating layer in the conventional TMRhead disclosed in JP-A-2001-52316, and the remaining layer of theinsulating layer in the first aspect corresponds to the secondinsulating layer in the conventional TMR head disclosed inJP-A-2001-52316.

However, in the first aspect, the layer of the insulating layer closestto the base extends over the end faces of the plurality of layers madeof different materials from one another and making up themagneto-resistive layer, and is in contact with the end faces of theplurality of layers with the same materials, so that themagneto-resistive device can be manufactured by a manufacturing methodaccording to a fifth aspect of the present invention, later described.Specifically, after patterning one or more of the constituent layersmaking up the magneto-resistive layer, end portions of the constituentlayers are not oxidized, but instead, an oxidizable layer is depositedin a region in which the one or more of the constituent layers have beenremoved by the patterning, and the deposited oxidizable layer can beoxidized to provide the layer of the insulating layer closest to thebase. On the contrary, in the conventional TMR head disclosed inJP-A-2001-52316, as described above, the first insulating layer isformed within the constituent layers which make up the magneto-resistivelayer (i.e., the first insulating layer is a layer produced by oxidizingend portions themselves of the constituent layers), and the firstinsulating layer is composed of a sequence of metal oxide films made ofmaterials different from one another corresponding to respectivematerials, respectively, which make up the magneto-resistive layer.Thus, the conventional TMR head disclosed in JP-A-2001-52316 cannot bemanufactured by the manufacturing method according to the fifth aspectof the present invention.

The result of a research made by the inventors, later described indetail, have revealed that the magneto-resistive device manufactured bythe manufacturing method according to the fifth aspect of the presentinvention, later described, can reduce the deterioration in thecharacteristics (increased resistance and reduced MR ratio) of themagneto-resistive device due to annealing. Presumably, this is becausewhen the oxidizable layer is deposited as a base material for oxidation,in addition to the constituent layers which make up themagneto-resistive layer, in a region in which the one or more of theconstituent layers have been removed by the patterning after patterningthe one or more of the constituent layers during the manufacturing, theinfluence exerted by adsorbates on the end face of the magneto-resistivelayer is reduced by the nature (the nature of absorbing and trappingoxygen, and the like) of the oxidizable layer.

Thus, the magneto-resistive device according to the first aspect can bemanufactured by the manufacturing method according to the fifth aspectof the present invention, later described, so that it can reduce thedeterioration in the characteristics thereof (increased resistance andreduced MR ratio) due to annealing. On the contrary, the conventionalTMR head disclosed in JP-A-2001-52316 cannot be manufactured by themanufacturing method according to the fifth aspect of the presentinvention, later described, so that it appears not to be able to reducethe deterioration in the characteristics thereof due to annealing.

In the first aspect, when the insulating layer includes two or morelayers, all the layers may be made of the same material. Here, two ormore layers made of the same material means that there is an interfaceexisting between the respective layers. In the conventional TMR headdisclosed in JP-A-2001-23131, the insulating layer formed around theconstituent layers of the magneto-resistive layer is a single-layer, andaccordingly does not have an interface in the laminating direction.Therefore, the conventional TMR head disclosed in JP-A-2001-23131 cannoteither manufactured by the manufacturing method according to the fifthaspect of the present invention, later described, and accordingly cannotreduce the deterioration in the characteristics thereof due toannealing.

Since the layer of the insulating layer closest to the base is made ofan oxide and has the insulating property, this layer will not provide abypass path for a sense current, and therefore will not cause areduction in the MR ratio due to the formation of a bypass path.

In a magneto-resistive device according to a second aspect of thepresent invention, the oxide is an oxide of a material selected from agroup consisting of Al, Si, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Zr, Nb,Mo, Hf, Ta, and W in the first aspect.

The second aspect enumerates preferred examples of materials for theoxide for making the layer of the insulating layer closest to the base,but the oxide is not limited to these examples in the first aspect.

In a magneto-resistive device according to a third aspect of the presentinvention, the effective region is a region in which a current flows ina direction substantially perpendicular to the film surface in themagneto-resistive layer in the first or second aspect.

The magneto-resistive device according to the third aspect shows anexample which employs a CPP structure. Since the CPP structure requiresan insulating layer for limiting a current path between the upperelectrode and lower electrode, a large technical meaning lies in thereduced deterioration in the characteristics due to annealing.

In a magneto-resistive device according to a fourth aspect of thepresent invention, the magneto-resistive layer includes a tunnel barrierlayer formed on one surface side of a free layer, a pinned layer formedon one surface side of the tunnel barrier layer opposite to the freelayer, and a pin layer formed on one surface side of the pinned layeropposite to the tunnel barrier layer, in the third aspect.

While the fourth aspect shows an example in which the third aspect isapplied to a TMR device, the third aspect is not limited to the TMRdevice but may be applied as well to a CPP-GMR device and the like.

A method of manufacturing a magneto-resistive device according to afifth aspect of the present invention includes the steps of depositingconstituent layers making up a magneto-resistive layer on a base,patterning one or more layers of the constituent layers, depositing anoxidizable layer in a region in which the one or more layers of theconstituent layers have been removed by the patterning, oxidizing theoxidizable layer, and depositing an insulating layer on the oxidizablelayer.

The manufacturing method according to the fifth aspect can manufacturethe magneto-resistive device which can reduce the deterioration in thecharacteristics thereof (increased resistance and reduced MR ratio) dueto annealing.

While the oxidizable layer is generally made of a metal or asemiconductor and has the electric conductivity, the manufacturingmethod according to the fifth aspect includes the step of oxidizing theoxidizable layer, so that even if the oxidizable layer eventuallyremains, the oxidizable layer merely remains as an oxide layer.Therefore, even if the oxidizable layer eventually remains, this layerwill not provide a bypass path for a sense current, and therefore willnot cause a reduction in the MR ratio due to the formation of a bypasspath.

In the manufacturing method according to the fifth aspect, the base maybe or may not be placed in the atmosphere after the step of patterningand before the step of depositing the oxidizable layer. When the base isplaced in the atmosphere, moisture, oxygen molecules, and the like willadsorb on end faces of remaining portions of the constituent layersafter they have been patterned. However, since the oxygen is thought tobe absorbed and trapped by the oxidizable layer after the deposition ofthe oxidizable layer, it is possible to reduce the deterioration in thecharacteristics of the magneto-resistive device due to annealing.However, it is preferred not to place the base in the atmosphere afterthe step of patterning and before the step of depositing the oxidizablelayer. The foregoing discussion is also applied to a sixteenth aspectand the like, later described.

Also, in the manufacturing method according to the fifth aspect, dryetching may or may not be performed for cleaning the surface immediatelybefore the step of depositing the oxidizable layer. Even without the dryetching performed to reduce moisture, oxygen molecules, and the like inthe atmosphere, adsorbed on the end faces of the remaining portions ofthe constituent layers after they have been patterned, the oxygen isthought to be absorbed and trapped by the oxidizable layer after thedeposition of the oxidizable layer. It is therefore possible to reducethe deterioration in the characteristics of the magneto-resistive devicedue to annealing even without necessarily performing the dry etching.However, the dry etching is preferably performed for cleaning thesurface immediately before the step of depositing the oxidizable layer.The foregoing discussion is applied as well to the sixteenth aspect andthe like, later described.

In a method of manufacturing a magneto-resistive device according to asixth aspect of the present invention, the step of oxidizing includes,in the fifth or sixth aspect, the step of placing the base in theatmosphere to naturally oxidize the oxidizable layer in the fifthaspect.

The natural oxidization as in the sixth aspect is preferably utilizedbecause the manufacturing process is simplified. Alternatively, the stepof oxidizing may include forced oxidization such as plasma oxidization,radical oxidization, ion beam oxidization, exposure to ozone, or thelike. When the forced oxidization is involved, the base may be or maynot be placed in the atmosphere after the step of depositing theoxidizable layer and before the step of depositing the insulating layer.Also, in the fifth aspect, the step of oxidizing is not limited to thenatural oxidization or forced oxidization, but may be a step ofoxidizing the oxidizable layer through absorption of oxygen from otherlayers by the action of annealing.

A method of manufacturing a magneto-resistive device according to aseventh aspect of the present invention further includes the step ofperforming dry etching for cleaning the surface immediately before thestep of depositing the insulating layer.

While the dry etching as in the seventh aspect is preferable forremoving impurities and the like, this dry etching is not necessarilyperformed in the fifth or sixth aspect.

In a method of manufacturing a magneto-resistive device according to aneighth aspect of the present invention, the step of performing dryetching includes the step of performing the dry etching in the samevacuum chamber in which the step of depositing the insulating layer isperformed in the seventh aspect.

When dry etching is performed for cleaning the surface immediatelybefore the step of depositing the insulating layer, the dry etching canbe readily performed in the same vacuum chamber in which the step ofdepositing the insulating layer is performed, as in the eighth aspect.Examples of dry etching for use in this event may be sputter etching andion beam etching.

In a method of manufacturing a magneto-resistive device according to aninth aspect of the present invention, the oxidizable layersubstantially remains after the step of performing dry etching and afterthe step of depositing the insulating layer in the seventh or eighthaspect.

In a method of manufacturing a magneto-resistive device according toaccording to a tenth aspect of the present invention, the oxidizablelayer is substantially removed by the step of performing dry etching inthe seventh or eighth aspect.

It has been confirmed by an experiment, later described, that thedeterioration in the characteristics of the magneto-resistive device dueto annealing can be reduced irrespective of whether the oxidizable layerremains or not after the dry etching as in the ninth and tenth aspects.

A method of manufacturing a magneto-resistive device according to aneleventh aspect of the present invention further includes, in the fifthor sixth aspect, the step of removing the oxidizing layer before thestep of depositing the insulating layer.

As mentioned above, It has been confirmed by an experiment, laterdescribed, that the deterioration in the characteristics of themagneto-resistive device due to annealing can be reduced even if theoxidizable layer does not eventually remain. Therefore, themanufacturing method according to the eleventh aspect can alsocontribute to reducing the deterioration in the characteristics of themagneto-resistive device due to annealing.

While the dry etching in the tenth aspect also serves as the step ofremoving in the eleventh aspect, the step of removing in the eleventhaspect is not limited to the dry etching for cleaning the surface.

A method of manufacturing a magneto-resistive device according to atwelfth aspect of the present invention includes the steps of depositingconstituent layers making up a magneto-resistive layer on a base,patterning one or more layers of the constituent layers, depositing alayer formed of a single-layer film, or a composite-layer film made of ametal and/or a semiconductor in a region in which the one or more layersof the constituent layers have been removed by the patterning, removingthe layer formed of a single-layer film or a composite-layer film madeof a metal and/or a semiconductor, and depositing an insulating layer inthe region in which the one or more layers of the constituent layershave been removed by the patterning after the step of removing thelayer. In this disclosure, “metal and/or semiconductor” means “one orboth of metal and semiconductor.”

In the manufacturing method according to the twelfth aspect, when anoxidizable layer is used for the layer formed of a single-layer film ora composite-layer film made of a metal and/or a semiconductor as in thesixth aspect described later, the oxidizable layer need not beeventually left as mentioned above, so that it is possible to reduce thedeterioration in the characteristics of the magneto-resistive device dueto annealing, in a manner similar to the fifth aspect.

On the other hand, in the manufacturing method according to the twelfthaspect, when a substantially oxidization-free layer is used for thelayer formed of a single-layer film or a composite-film made of a metaland/or a semiconductor, it is thought that this layer does not have thenature of absorbing and trapping oxygen, so that the resultingmagneto-resistive device cannot reduce the deterioration in thecharacteristics thereof due to annealing by the same principle as themanufacturing method according to the fifth aspect. However, this layerdoes have a barrier-like nature to oxygen and the like. Therefore,according to the twelfth aspect, when a substantially oxidization-freelayer is used for the layer formed of a single-layer film or acomposite-film made of a metal and/or a semiconductor, the layer formedof a single-layer film or a composite-film made of a metal and/or asemiconductor is deposited after the step of patterning and before thebase is placed in the atmosphere, such that even if the base is placedin the atmosphere before the insulating layer is deposited, the endfaces of the portions of the constituent layers, which remain after thepatterning, are protected by the barrier-like nature of the layer formedof a single-layer film or a composite-film made of a metal and/or asemiconductor. Consequently, according to the manufacturing method inthe twelfth aspect, even if a substantially oxidization-free layer isused for the layer formed of a single-layer film or a composite-layerfilm made of a metal and/or a semiconductor, the resultingmagneto-resistive device can reduce the deterioration in thecharacteristics thereof due to annealing.

Since the manufacturing method according to the twelfth aspect includesthe step of removing, the layer formed of a single-layer film or acomposite-layer film made of a metal and/or a semiconductor does noteventually remain, so that even if the layer does not have a sufficientinsulating property, the layer will not provide a bypass path for asense current. For this reason, the manufacturing method according tothe twelfth aspect does not necessarily require the step of oxidizingthe oxidizable layer, which is a constituent step of the manufacturingmethod according to the fifth aspect, not only when a substantiallyoxidization-free layer is used for the layer formed of a single-layerfilm or a composite-layer film made of a metal and/or a semiconductorbut also when an oxidizable layer is used for the layer formed of asingle-layer film or a composite-layer film made of a metal and/or asemiconductor.

In the twelfth aspect, the base may or may not be placed in theatmosphere after the step of depositing the layer formed of asingle-layer film or a composite-layer film made of a metal and/or asemiconductor and before the step of depositing the insulating layer.

A method of manufacturing a magneto-resistive device according tothirteenth aspect of the present invention further includes, in thetwelfth aspect, the step of performing dry etching for cleaning thesurface immediately before the step of depositing the insulating layer,wherein the step of performing dry etching additionally serves as thestep of removing.

It is preferable that the dry etching for cleaning the surfaceadditionally serves as the step of removing as in the thirteenth aspect,because the process can be simplified as compared with both steps areperformed in separation.

In a method of manufacturing a magneto-resistive device according to afourteenth aspect of the present invention, the step of performing dryetching includes the step of performing the dry etching in the samevacuum chamber in which the step of depositing the insulating layer isperformed in the thirteenth aspect.

The dry etching is preferably performed in the same vacuum chamber as inthe fourteenth aspect, because the dry etching for cleaning the surfacecan be readily performed. Examples of dry etching for use in this eventmay be sputter etching and ion beam etching.

In a method of manufacturing a magneto-resistive device according to afifteenth aspect of the present invention, the layer formed of asingle-layer film or a composite-layer film made of a metal and/or asemiconductor is formed of a single-layer film or a composite-layer filmmade of one or more materials selected from a group consisting of Al,Si, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Zr, Nb, Mo, Hf, Ta, W, Ru, Rh,Pd, Ag, Re, Os, Ir, Pt, and Au, in any of the twelfth to fourteenthaspects.

The fifteenth aspect enumerates preferred examples of materials for thelayer formed of a single-layer film or a composite-layer film made of ametal and/or a semiconductor, but the material is not limited to theseexamples in the twelfth to fourteenth aspects. In the materials listedabove, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt, and Au are examples ofsubstantially oxidization-free materials.

In a method of manufacturing a magneto-resistive device according to asixteenth aspect of the present invention, the layer formed of asingle-layer film or a composite-layer film made of a metal and/or asemiconductor is an oxidizable layer, in any of the twelfth tofourteenth aspects.

In the manufacturing method according to the sixteenth aspect, since anoxidizable layer is used for the layer formed of a single-layer film ora composite-layer film made of a metal and/or a semiconductor, thenature of the oxidizing layer to absorb and trap oxygen can be utilizedto further reduce the deterioration in the characteristics of themagneto-resistive device due to annealing. However, in the twelfth tofourteenth aspects, a substantially oxidization-free layer may be usedfor the layer formed of a single-layer film or a composite-layer filmmade of a metal and/or a semiconductor, as described above.

In a method of manufacturing a magneto-resistive device according to aseventeenth aspect of the present invention, the oxidizable layer isformed of a single-layer film or a composite-layer film made of one ormore materials selected from a group consisting of Al, Si, Ti, V, Cr,Mn, Fe, Ni, Co, Cu, Zn, Zr, Nb, Mo, Hf, Ta, and W, in any of the fifthto eleventh and sixteenth aspects.

The seventeenth aspect enumerates preferred examples of materials forthe oxidizable layer, but the material is not limited to these examplesin the fifth to eleventh and sixteenth aspects.

In a method of manufacturing a magneto-resistive device according to aneighteenth aspect, the magneto-resistive device includes an effectiveregion effectively involved in detection of magnetism in themagneto-resistive layer, wherein the effective region is a region inwhich a current flows in a direction substantially perpendicular to thefilm surface in the magneto-resistive layer, in any of the fifth toseventeenth aspects.

The magneto-resistive device according to the eighteenth aspect shows anexample which employs a CPP structure. Since the CPP structure requiresan insulating layer for limiting a current path between the upperelectrode and lower electrode, a large technical meaning lies in thereduced deterioration in the characteristics due to annealing.

In a method of manufacturing a magneto-resistive device according to anineteenth aspect, the magneto-resistive layer includes a tunnel barrierlayer formed on one surface side of a free layer, a pinned layer formedon one surface side of the tunnel barrier layer opposite to the freelayer, and a pin layer formed on one surface side of the pinned layeropposite to the tunnel barrier layer, in any of the fifth to eighteenthaspects.

While the nineteenth aspect shows an example in which the eighteenthaspect is applied to a TMR device, the eighteenth aspect is not limitedto the TMR device but may be applied as well to a CPP-GMR device and thelike.

A magnetic head according to a twentieth aspect of the present inventionincludes a base, and a magneto-resistive device supported by the base,wherein the magneto-resistive device is the magneto-resistive deviceaccording to any of the first to fourth aspects or the magneto-resistivedevice manufactured by the manufacturing method according to any of thefifth to nineteenth aspects.

According to the twentieth aspect, since the magnetic head uses themagneto-resistive device according to any of the first to fourth aspectsor the magneto-resistive device manufactured by the manufacturing methodaccording to any of the fifth to nineteenth aspects, the magnetic headcan reduce the deterioration in the characteristics of themagneto-resistive device due to annealing. Therefore, for example, whenthe magneto-resistive device is combined with another recording deviceto provide a composite magnetic head, it is possible to improve thecharacteristics of the magneto-resistive device, even if the device isannealed in the course of the manufacturing of the recording device, toachieve an increased S/N ratio of a read signal, and the like.

A head suspension assembly according to a twenty first aspect of thepresent invention includes a magnetic head, and a suspension forsupporting the magnetic head mounted near a leading end thereof, whereinthe magnetic head is the magnetic head according to the twentiethaspect.

According to the twenty first aspect, since the head suspension assemblyemploys the magnetic head according to the twentieth aspect, therecording density can be increased for a magnetic disk apparatus or thelike.

A magnetic disk apparatus according to a twenty second aspect of thepresent invention includes the head suspension assembly according to thetwenty first aspect, an arm for supporting the head suspension assembly,and an actuator for moving the arm to position a magnetic head.

According to the twenty second aspect, since the magnetic disk apparatusemploys the head suspension assembly according to the twenty firstaspect, the recording density can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general perspective view schematically illustrating amagnetic head according to a first embodiment of the present invention;

FIG. 2 is an enlarged cross-sectional view schematically illustrating aportion of a TMR device and an inductive magnetic transducing device inthe magnetic head illustrated in FIG. 1;

FIG. 3 is a general sectional view taken along a line A-A′ indicated byarrows in FIG. 2;

FIG. 4 is a further enlarged view around the TMR device in FIG. 2;

FIG. 5 is a further enlarged view around the TMR device in FIG. 3;

FIGS. 6A and 6B are diagrams schematically illustrating a step whichmakes up a magnetic head manufacturing method according to a secondembodiment of the present invention;

FIGS. 7A and 7B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thesecond embodiment of the present invention;

FIGS. 8A and 8B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thesecond embodiment of the present invention;

FIGS. 9A and 9B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thesecond embodiment of the present invention;

FIGS. 10A and 10B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thesecond embodiment of the present invention;

FIGS. 11A and 11B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thesecond embodiment of the present invention;

FIGS. 12A and 12B are diagrams schematically illustrating a step whichmakes up a magnetic head manufacturing method according to a thirdembodiment of the present invention;

FIGS. 13A and 13B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thethird embodiment of the present invention;

FIGS. 14A and 14B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thethird embodiment of the present invention;

FIGS. 15A and 15B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thethird embodiment of the present invention;

FIGS. 16A and 16B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thethird embodiment of the present invention;

FIGS. 17A and 17B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thethird embodiment of the present invention;

FIGS. 18A and 18B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thethird embodiment of the present invention;

FIGS. 19A and 19B are diagrams schematically illustrating a further stepwhich makes up the magnetic head manufacturing method according to thethird embodiment of the present invention;

FIG. 20 is an enlarged cross-sectional view schematically illustrating aportion of a TMR device and an inductive magnetic transducing device ina magnetic head manufactured by the magnetic head manufacturing methodaccording to the third embodiment of the present invention;

FIG. 21 is a general sectional view taken along a line B-B′ indicated byarrows in FIG. 20;

FIG. 22 is a further enlarged view around the TMR device in FIG. 20;

FIG. 23 is a further enlarged view around the TMR device in FIG. 21;

FIG. 24 is a perspective view generally illustrating the configurationof a main portion of a magnetic disk apparatus according to a fifthembodiment of the present invention;

FIG. 25 is a graph showing a shift ratio of the resistance of respectivesamples; and

FIG. 26 is a graph showing a shift ratio of the MR ratio of respectivesamples.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following, a magneto-resistive device and a method ofmanufacturing the same, and a magnetic head, a head suspension assemblyand a magnetic disk apparatus which use the magneto-resistive deviceaccording to the present invention will be described with reference tothe accompanying drawings.

First, a magnetic head according to a first embodiment of the presentinvention will be described with reference to FIGS. 1 to 5.

FIG. 1 is a general perspective view schematically illustrating themagnetic head according to the first embodiment of the presentinvention. FIG. 2 is an enlarged cross-sectional view schematicallyillustrating a portion of a TMR device 2 and an inductive magnetictransducing device 3 in the magnetic head illustrated in FIG. 1. FIG. 3is a general sectional view taken along a line A-A′ indicated by arrowsin FIG. 2. FIG. 4 is a further enlarged view illustrating around the TMRdevice 2 in FIG. 2. FIG. 5 is a further enlarged view around the TMRdevice 2 in FIG. 3. For facilitating the understanding, an X-axis, aY-axis and a Z-axis, orthogonal to one another, are defined as shown inFIG. 1 to 5 (the same applies to figures later described). The Z-axisdirection indicated by the arrow is referred to as the “+Z-direction” or“+Z-side,” and the opposite direction is referred to as the“−Z-direction” or “−Z-side.” The same is applied to the X-axis directionand Y-axis direction. The X-axis direction is the same as a direction inwhich a magnetic recording medium is moved. The Z-axis direction is thesame as a track width direction of the TMR device 2.

As illustrated in FIG. 1, the magnetic head according to the firstembodiment comprises a slider 1 as a base; the TMR device 2 as amagneto-resistive device for use as a magnetic head device forreproduction; an inductive magnetic transducing device 3 as a magnetichead device for recording; and a protection film 4 made of a DLC film orthe like, and is configured as a composite magnetic head. However, themagnetic head according to the present invention may comprise only theTMR device 2. Also, while the magnetic head of the first embodimentcomprises one each of the devices 2, 3, the numbers of these devices arenot limited in any sense.

The slider 1 has rails 11, 12 on a surface opposite to a magneticrecording medium, and the surfaces of the rails 11, 12 define airbearing surfaces (ABS). In the example illustrated in FIG. 1, there aretwo rails 11, 12, but the number of rails is not limited to two. Forexample, the slider 1 may have one to three rails, or the ABS may be aflat surface without rails. In addition, the ABS may be formed with avariety of geometric shapes for improving a floating characteristic andthe like. The magnetic head according to the present invention may haveany type of slider.

In the first embodiment, the protection film 4 is applied only on thesurfaces of the rails 11, 12, so that the surface of the protection film4 defines the ABS. Actually, the protection film 4 may be applied on theentire surface of the slider 1 opposite to a magnetic recording medium.While the protection film 4 is preferably provided, the protection film4 may not be necessarily provided.

The TMR device 2 and inductive magnetic transducing device 3 aredisposed on the rail 12 near an air outlet end TR, as illustrated inFIG. 1. A direction in which a recording medium is moved is identical tothe X-axis direction in FIG. 1, and also identical to a direction inwhich air flows when the magnetic recording medium is rapidly moved. Airenters from an air inlet end LE and exits from the air outlet end TR.The slider 1 is provided on an end face of the air outlet end TR withbonding pads 5 a, 5 b connected to the TMR device 2, and bonding pads 5c, 5 d connected to the inductive magnetic transducing device 3.

As illustrated in FIGS. 2 and 3, the TMR device 2 and inductive magnetictransducing device 3 are laminated on an underlying layer 16 depositedon a ceramic base 15 which constitutes the slider 1. The ceramic base 15is generally made of AlTiC (Al2O3-TiC), SiC or the like. When Al2O3-TiCis used, an insulating film made, for example, of Al₂O₃ is used for theunderlying layer 16 since Al2O3-TiC is electrically conductive. Theunderlying layer 16 may not be provided in some cases.

As illustrated in FIGS. 4 and 5, the TMR device 2 comprises a lowerelectrode 21 formed on the underlying layer 16; an upper electrode 31formed overlying the lower electrode 21 (opposite to the base 15); and alower metal layer (lower layer) 22, a lower metal layer (upper layer)23, a pin layer 24, a pinned layer 25, a tunnel barrier layer 26, a freelayer 27, and an upper metal layer (cap layer) 28 as a non-magneticmetal layer which serves as a protection layer, and an upper metal layer29 as an underlying layer of the upper electrode 31 which are laminatedin this order from the lower electrode 21 between the electrodes 21, 31.The pin layer 24, pinned layer 25, tunnel barrier layer 26 and freelayer 27 constitute a magneto-resistive layer. While the actual TMRdevice 2 typically has a laminate structure compose of a larger numberof layers, rather than the laminate structure composed of the number oflayers as illustrated, the illustrated magnetic head represents alaminate structure minimally required for the basic operation of the TMRdevice 2 for simplifying the description.

In the first embodiment, the lower electrode 21 and upper electrode 31are additionally used as a lower magnetic shield and an upper magneticshield, respectively. The electrodes 21, 31 are formed of a magneticmaterial, for example, NiFe or the like. Though not shown, theseelectrodes 21, 31 are electrically connected to the aforementionedbonding pads 5 a, 5 b, respectively. It should be understood that alower magnetic shield and an upper magnetic shield may be provided inaddition to the lower electrode 21 and upper electrode 31.

The lower metal layer 22 is an electrically conductive material which iscomprised, for example, of a Ta layer or the like. The lower metal layer23 is an electrically conductive material which is comprised, forexample, of an NiFe layer or the like. In the first embodiment. Thelower metal layer 23 is formed only coextensively to themagneto-resistive layer, while the lower metal layer 22 widely extendsover the electrode 21. Alternatively, the lower metal layer 23 may alsobe extended widely, or the lower metal layer 22 may be formed onlycoextensively to the magneto-resistive layer.

The pin layer 24, which is comprised of an antiferromagnetic layer, ispreferably formed, for example, of an Mn-based alloy such as PtMn, IrMn,RuRhMn, FeMn, NiMn, PdPtMn, RhMn, CrMnPt, or the like. The pinned layer25 and free layer 27 are each comprised of a ferromagnetic layer formedof such a material as Fe, Co, Ni, FeCo, NiFe, CoZrNb, FeCoNi, or thelike. The pinned layer 25 has its magnetization direction fixed in apredetermined direction by an exchange bias magnetic field between thepinned layer 25 and the pin layer 24. On the other hand, the free layer27 freely varies its magnetization direction in response to an externalmagnetic field which is basically magnetic information. The pinned layer25 and free layer 27 are not limited to single-layers, but mayimplemented, for example, by a laminate comprised of a combination of apair of magnetic layers in anti-ferromagnetic coupling and anon-magnetic metal layer sandwiched therebetween. Such a laminate may beformed, for example, of three ferromagnetic layers made of CoFe/Ru/CoFe.In the first embodiment, the pin layer 24, pinned layer 25, tunnelbarrier layer 26 and free layer 27 are laminated in this order from thelower electrode 21. Alternatively, the free layer 27, tunnel barrierlayer 26, pinned layer 25 and pin layer 24 may be laminated in thisorder from the lower electrode 21. The tunnel barrier layer 26 isformed, for example, of a material such as Al2O3, NiO, GdO, MgO, Ta2O5,MoO2, TiO2, WO2, or the like.

The upper metal layer 28 is formed of a single-layer film or acomposite-layer film made of simple Ta, Rh, Ru, Os, W, Pd, Pt, or Au, oran alloy made up of two or more of these elements in combination.

The upper metal layer 29, serving as the underlying layer of the upperelectrode 31, is made of an electrically conductive material formed of anon-magnetic metal such as Ta or the like. In the first embodiment, theupper metal layer 29 is provided for holding a magnetic shield gap (agap between the electrodes 21, 31) of a desired dimension. However, theupper metal layer 29 may not be provided.

As illustrated in FIGS. 3 and 5, a magnetic domain control layer 32 forapplying a biasing magnetic field to the free layer 27 for magneticdomain control is formed on each side of the magneto-resistive layer inthe Z-axis direction. The magnetic domain control layer 32 is formed,for example, of a hard magnetic material such as Cr/CoPt (cobaltplatinum alloy), Cr/CoCrPt (cobalt chromium platinum alloy), TiW/CoPt,TiW/CoCrPt, or the like. Alternatively, the magnetic domain controllayer 32 may be, for example, a layer using a switched connection inwhich a soft magnetic layer and an anti-ferromagnetic layer arelaminated. Two insulating layers 33, 34 are formed under the magneticdomain control layer 32. The insulating layers 33, 34 also intervenebetween end faces of the magnetic domain control layer 32 and layers23-28 on the +Z-side and −Z-side, such that the layers 23-28 are notelectrically short-circuited by the magnetic domain control layer 32.The upper insulating layer 34 is made of Al2O3 or SiO2.

In the first embodiment, the insulating layer 33, closest to the base 15of the two insulating layers 33, 34, is formed of a single-layer filmmade of a metal or semiconductor oxide, and extends over the end facesof the layers 23-28 such that it is in contact with the end faces of thelayers 23-28 with the same materials. The layers 23-28 are made of theaforementioned materials, respectively, different from one another.However, some of layers 23-28 are made of the same materials.Specifically, the insulating layer 33 may be made, for example, of anoxide of Al, Si, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Zr, Nb, Mo, Hf, Ta,or W. While the insulating layers 33, 34 may be made of the samematerials, an interface also exists between the two layers in that case.

Also, as illustrated in FIGS. 2 and 4, two insulating layers 30, 35 areformed between the lower metal layer 22 and upper metal layer 29 in aregion in which the layers 32-34 are not formed. The two insulatinglayers 30, 35 cover the end faces of the layers 23-28 on the −Y-side.The upper insulating layer 30 is made of Al2O3 or SiO2.

In the first embodiment, the insulating layer 35, closest to the base 15of the two insulating layers 30, 35, is formed of a single-layer filmmade of a metal or semiconductor oxide, similar to the insulating layer33, and extends over the end faces of the layers 23-28 such that it isin contact with the end faces of the layers 23-28 with the samematerials. Specifically, the insulating layer 35 may be made, forexample, of an oxide of Al, Si, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Zr,Nb, Mo, Hf, Ta, or W. While the insulating layers 30, 35 may be made ofthe same materials, an interface also exists between the two layers inthat case.

In the first embodiment, the two insulating layers 33, 34 on the +Z-sideand −Z-side of the magneto-resistive layer, as well as the twoinsulating layers 35, 30 on the −Y-side of the magneto-resistive layercomprise an insulating layer which is formed to be in contact with aneffective region effectively involved in the detection of magnetism inthe magneto-resistive layer (in the first embodiment, a region in whicha current flows in a direction substantially perpendicular to the filmsurface in the magneto-resistive layer), without overlapping with thiseffective region.

As illustrated in FIGS. 2 and 3, the inductive magnetic transducingdevice 3 comprises the upper electrode 31 which is additionally used asa lower magnetic layer for the device 3; an upper magnetic layer 36; acoil layer 37; a write gap layer 38 made of alumina or the like; aninsulating layer 39 made of a thermosetting photoresist (for example, anorganic resin such as a novolac resin); a protection layer 40 made ofalumina or the like, and the like. NiFe, FeN or the like, for example,is used as a material for the upper magnetic layer 36. Leading ends ofthe upper electrode 31, which is additionally used as the lower magneticlayer, and the upper magnetic layer 36 are formed as a lower pole 31 aand an upper pole 36 a which oppose each other through the write gaplayer 38 made of alumina or the like in an infinitesimal thickness. Thelower pole 31 a and upper pole 36 a write information on a magneticrecording medium. The upper electrode 31, which is additionally used asthe lower magnetic layer, and the upper magnetic layer 36 are coupled toeach other at a joint 41 at which a yoke is opposite to the lower pole31 a and upper pole 36 a so as to complete a magnetic circuit. Withinthe insulating layer 39, a coil layer 37 is formed such that it isspirally wound around the joint 41 of the yoke. The coil layer 37 hasboth ends electrically connected to the bonding pads 5 c, 5 d. The coillayer 37 is arbitrary in the number of turns and the number of layers.Also, the inductive magnetic transducing device 3 may be arbitrary instructure. The upper electrode 31 may be divided into two layers acrossan insulating layer made of Al2O3, SiO2 or the like in order to separatethe role of the lower magnetic layer in the inductive magnetictransducing device 3 from the role of the upper electrode in the TMRdevice 2.

Next, description will be made on a method of manufacturing a magnetichead according to a second embodiment of the present invention. Thismagnetic head manufacturing method is provided for manufacturing themagnetic head according to the first embodiment, and includes a methodof manufacturing a magneto-resistive device according to one embodimentof the present invention.

First, a wafer process is performed. Specifically, a wafer 101 made ofAl2O3-TiC, SiC or the like is provided for making a base 15. Using thethin film forming technology and the like, the aforementioned layers areformed in a large number of magnetic head forming regions in matrix onthe wafer 101 to provide the aforementioned structure.

The outline of the wafer process will be described with reference toFIGS. 6 to 11. FIGS. 6 to 11 are diagrams schematically illustratingrespective steps which make up the wafer process, wherein FIGS. 6A, 7A,8A, 9A, 10A and 11A are general plan views, respectively; FIG. 6B is ageneral cross-sectional view taken along a line C-D in FIG. 6A; FIG. 7Bis a general cross-sectional view taken along a line C-D in FIG. 7A;FIG. 8B is a general cross-sectional view taken along a line C-D in FIG.8A; FIG. 9B is a general cross-sectional view taken along a line E-F inFIG. 9A; FIG. 10B is a general cross-sectional view taken along a lineE-F in FIG. 10A; and FIG. 11B is a general cross-sectional view takenalong a line E-F in FIG. 11A. In FIGS. 7A and 8A, TW indicates the widthof a track defined by the TMR device 2.

First, in the wafer process, the underlying layer 16, lower electrode21, lower metal layer 22, lower metal layer 23, pin layer 24, pinnedlayer 25, tunnel barrier layer 26, free layer 27, and upper metal layer28 are sequentially laminated on the wafer 101 (FIGS. 6A and 6B). Inthis event, the lower electrode 21 is formed, for example, by a platingmethod, while the other layers are formed, for example, by a sputteringmethod. Subsequently, the substrate in this state is once left in theatmosphere. In this event, an oxide film (not shown) is formed on thetop face of the upper metal layer 28 (FIGS. 6A and 6B).

Next, the lower metal layer 23, pin layer 24, pinned layer 25, tunnelbarrier layer 26, free layer 27, upper metal layer 28, and the oxidefilm on the upper metal layer 28 are partially removed by first ionmilling using a resist mask (not shown) for first lift-off forpatterning. Next, in a region removed by the first ion milling, anoxidizable layer 33′ (this layer is hereinafter referred as the“deterioration reducing layer” for convenience of description becausethe layer acts to reduce the deterioration in the characteristics of thefabricated TMR device 2 due to annealing) is formed while leaving theresist mask for the first lift-off as it is (FIGS. 7A and 7B). It shouldbe noted that in FIGS. 7A and 7B, the resist mask for the first lift-offis omitted in the illustration.

From the first ion milling to this stage, the foregoing process isperformed within the same vacuum chamber, so that the substrate 101 willnever be placed in the atmosphere.

In the second embodiment, the deterioration reducing layer 33′ is formedof a single-layer film made of a metal or a semiconductor. Thedeterioration reducing layer 33′ should be oxidized to be the insulatinglayer 33 in the magnetic head according to the first embodiment.Specifically, the deterioration reducing layer 33′ may be formed of asingle-layer film made of, for example, Al, Si, Ti, V, Cr, Mn, Fe, Ni,Co, Cu, Zn, Zr, Nb, Mo, Hf, Ta, or W.

Subsequently, the substrate 101 having the deterioration reducing layer33′ deposited thereon is placed in the atmosphere to naturally oxidizethe deterioration reducing layer 33′. As a result, the deteriorationreducing layer 33′ is changed into an oxide layer which serves as theinsulating layer 33.

Next, in the same vacuum chamber in which the insulating layer 34 isdeposited, the resulting product is dry etched by sputter etching, ionbeam etching, or the like for cleaning the surface thereof. In thesecond embodiment, the previously deposited deterioration reducing layer33′ is set to have a relatively large thickness in consideration of theconditions for this dry etching, such that the insulating layer 33remains after the dry etching.

Next, the insulating layer 34 is formed on the insulating layer 33 withthe resist mask for the first lift-off being left as it is, and themagnetic domain control layer 32 is further formed on the insulatinglayer 34. Subsequently, the resist mask for the first lift-off isremoved to complete the lift-off for the layers 33, 34, 32 (FIGS. 8A and8B).

Next, the lower metal layer 23, pin layer 24, pinned layer 25, tunnelbarrier layer 26, free layer 27, upper metal layer 28, oxide film (notshown) on the upper metal layer 28 as mentioned above, insulating layers33, 34, and magnetic domain control layer 32 are partially removed bysecond ion milling using a resist mask (not shown) for second lift-offfor patterning while leaving a strip portion which has a necessary width(width in the Y-axis direction) with respect to the height direction ofthe TMR device 2 and extends in the Z-axis direction by a predeterminedlength. Subsequently, in a region removed by the second ion milling, anoxidizable layer 35′ (this layer is hereinafter referred as the“deterioration reducing layer” as well for convenience of descriptionbecause the layer also acts to reduce the deterioration in thecharacteristics of the fabricated TMR device 2 due to annealing) isformed while leaving the resist mask for the second lift-off as it is(FIGS. 9A and 9B). It should be noted that in FIGS. 9A and 9B, theresist mask for the second lift-off is omitted in the illustration.

From the second ion milling to this stage, the foregoing process isperformed within the same vacuum chamber, so that the substrate 101 willnever be placed in the atmosphere.

In the second embodiment, the deterioration reducing layer 35′ is formedof a single-layer film made of a metal or a semiconductor. Thedeterioration reducing layer 35′ should be oxidized to be the insulatinglayer 35 in the magnetic head according to the first embodiment.Specifically, the deterioration reducing layer 35′ may be formed of asingle-layer film made of, for example, Al, Si, Ti, V, Cr, Mn, Fe, Ni,Co, Cu, Zn, Zr, Nb, Mo, Hf, Ta, or W.

Subsequently, the substrate 101 having the deterioration reducing layer35′ deposited thereon is placed in the atmosphere to naturally oxidizethe deterioration reducing layer 35′. As a result, the deteriorationreducing layer 35′ is changed into an oxide layer which serves as theinsulating layer 35.

Next, in the same vacuum chamber in which the insulating layer 30 isdeposited, the resulting product is dry etched by sputter etching, ionbeam etching, or the like for cleaning the surface thereof. In thesecond embodiment, the previously deposited deterioration reducing layer35′ is set to have a relatively large thickness in consideration of theconditions for this dry etching, such that the insulating layer 35remains after the dry etching.

Next, the insulating layer 30 is formed on the insulating layer 35 withthe resist mask for the second lift-off being left as it is.Subsequently, the resist mask for the second lift-off is removed tocomplete the lift-off for the layers 35, 30 (FIGS. 10A and 10B).

Subsequently, in the same vacuum chamber in which the upper metal layer29 is formed, the resulting product is dry etched by sputter etching,ion beam etching, or the like to remove the oxide film formed on the topface of the upper metal layer 28.

Next, the upper metal layer 29 is formed by a sputtering method or thelike, and the upper electrode 31 is formed by a plating method or thelike (FIGS. 11A and 11B).

Finally, the gap layer 38, coil layer 37, insulating layer 39, uppermagnetic layer 36, and protection layer 40 are formed, and theelectrodes 5 a-5 d are formed. Also, the resulting product is annealedfor curing the insulating layer (thermosetting photoresist) 39. By now,the wafer process is completed.

Next, magnetic heads are completed through a known process for the waferwhich has undergone the wafer process. Briefly describing, each bar(bar-shaped magnetic head aggregate) having a plurality of magneticheads arranged in a line on the base is sawed from the wafer. Next, thebar is lapped on its ABS side for setting a throat height, an MR height,and the like for the bar. Next, a protection film 4 is formed on thesurface of the ABS side, and rails 11, 12 are formed by etching or thelike. Finally, the bar is cut by machining into individual magneticheads. In this manner, the magnetic heads are completed in accordancewith the first embodiment.

It has been confirmed by an experiment, later described, that themagnetic head according to the first embodiment manufactured by themanufacturing method according to the second embodiment can reduce thedeterioration in the characteristics of the TMR device 2 (increasedresistance and reduced MR ratio) due to the annealing.

It is thought that the foregoing benefit results from the deteriorationreducing layers 33′, 35′ which have the nature of absorbing and trappingoxygen, and the like.

Specifically, oxygen sticking on the end faces of the layers 23-28,exposed by the first ion milling, are trapped by the deteriorationreducing layer 33′. Also, oxygen sticking on the end faces of the layers23-28, exposed by the second ion milling, are trapped by thedeterioration reducing layer 35′. It is therefore thought that it ispossible to reduce the deterioration in the characteristics of the TMRdevice 2 (increased resistance and reduced MR ratio) due to theannealing.

In the present invention, the manufacturing method according to thesecond embodiment may be modified as described below. The modificationsdescribed below can be combined as appropriate for application to themanufacturing method according to the second embodiment.

First, the deterioration reducing layer 33′ may be formed of acomposite-layer film made of a metal and/or a semiconductor. In thisevent, each of layers which make up the composite-layer film may bemade, for example, of Al, Si, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Zr, Nb,Mo, Hf, Ta, or W. This can be applied to the deterioration reducinglayer 35′ as well.

Second, the dry etching for cleaning the surface may be omitted beforethe deposition of the insulating layer 34. Similarly, the dry etchingfor cleaning the surface may be omitted before the deposition of theinsulating layer 30.

Third, the oxidization of the deterioration reducing layer 33′ is notlimited to the natural oxidization, but the deterioration reducing layer33′ may be forcedly oxidized, for example, by plasma oxidization,radical oxidization, ion beam oxidization, exposure to ozone, and thelike. Alternatively, for example, the substrate 101 may be placed in theatmosphere after the first ion milling and before the deposition of thedeterioration reducing layer 33′ to adsorb moisture and oxygen moleculesin the air onto the end faces of the layers 23-28. Then, thedeterioration reducing layer 33′ may be deposited in this state suchthat oxygen and the like adsorbed on the end faces are trapped into thedeterioration reducing layer 33′, thereby oxidizing the deteriorationreducing layer 33′. These aspects can be applied to the oxidization ofthe deterioration reducing layer 35′ as well.

Fourth, one of the deterioration reducing layers 33′, 35′ may not beformed. Though both are preferably formed as in the second embodiment,either the deterioration reducing layer 33′ or 35′ may be formed toprovide the advantage of reducing the deterioration in thecharacteristics of the TMR device 2 due to annealing.

Fifth, the substrate 101 may be placed in the atmosphere after the firstion milling and before the deposition of the deterioration reducinglayer 33′. Similarly, the substrate 101 may be placed in the atmosphereafter the second ion milling and before the deposition of thedeterioration reducing layer 35′.

Next, description will be made on a method of manufacturing a magnetichead according to a third embodiment of the present invention.

The third embodiment is identical to the second embodiment except forthe wafer process. The wafer process in the third embodiment differsfrom the wafer process in the second embodiment in that thedeterioration reducing layer 33′ is deposited in a relatively smallthickness so that the insulating layer 33 is removed by the dry etchingfor cleaning the surface before the deposition of the insulating layer34, and that the deterioration reducing layer 35′ is deposited in arelatively small thickness so that the insulating layer 35 is removed bythe dry etching for cleaning the surface before the deposition of theinsulating layer 30.

Therefore, the steps themselves are the same both in the thirdembodiment and the second embodiment. However, the third embodimentdiffers from the second embodiment in the process diagram and thestructure of the manufactured magnetic head resulting from the foregoingdifferences.

In the third embodiment, the wafer process is also performed firstly.Specifically, a wafer 101 made of Al2O3-TiC, SiC or the like is providedfor making a base 15. Using the thin film forming technology and thelike, the aforementioned layers are formed in a large number of magnetichead forming regions in matrix on the wafer 101 to provide theaforementioned structure.

The outline of the wafer process will be described with reference toFIGS. 12 to 19. FIGS. 12 to 19 are diagrams schematically illustratingrespective steps which make up the wafer process, wherein FIGS. 12A,13A, 14A, 15A, 16A, 17A, 18A and 19A are general plan views,respectively; FIG. 12B is a general cross-sectional view taken along aline C-D in FIG. 12A; FIG. 13B is a general cross-sectional view takenalong a line C-D in FIG. 13A; FIG. 14B is a general cross-sectional viewtaken along a line C-D in FIG. 14A; FIG. 15B is a generalcross-sectional view taken along a line C-D in FIG. 15A; FIG. 16B is ageneral cross-sectional view taken along a line E-F in FIG. 16A; FIG.17B is a general cross-sectional view taken along a line E-F in FIG.17A; FIG. 18B is a general cross-sectional view taken along a line E-Fin FIG. 18A; and FIG. 19B is a general cross-sectional view taken alonga line E-F in FIG. 19A. In FIGS. 12 to 19, elements identical orcorresponding to those in FIGS. 1 to 11 are designated by the samereference numerals. In FIGS. 13A, 14A and 15A, TW indicates the width ofa track defined by the TMR device 2.

First, in the wafer process, the underlying layer 16, lower electrode21, lower metal layer 22, lower metal layer 23, pin layer 24, pinnedlayer 25, tunnel barrier layer 26, free layer 27, and upper metal layer28 are sequentially laminated on the wafer 101 (FIGS. 12A and 12B). Inthis event, the lower electrode 21 is formed, for example, by a platingmethod, while the other layers are formed, for example, by a sputteringmethod. Subsequently, the substrate in this state is once left in theatmosphere. In this event, an oxide film (not shown) is formed on thetop face of the upper metal layer 28 (FIGS. 12A and 12B).

Next, the lower metal layer 23, pin layer 24, pinned layer 25, tunnelbarrier layer 26, free layer 27, upper metal layer 28, and the oxidefilm on the upper metal layer 28 are partially removed by first ionmilling using a resist mask (not shown) for first lift-off forpatterning. Next, in a region removed by the first ion milling, adeterioration reducing layer 33′ is formed while leaving the resist maskfor the first lift-off as it is (FIGS. 13A and 13B). It should be notedthat in FIGS. 13A and 13B, the resist mask for the first lift-off isomitted in the illustration.

From the first ion milling to this stage, the foregoing process isperformed within the same vacuum chamber, so that the substrate 101 willnever be placed in the atmosphere.

Subsequently, the substrate 101 having the deterioration reducing layer33′ deposited thereon is placed in the atmosphere to naturally oxidizethe deterioration reducing layer 33′. As a result, the deteriorationreducing layer 33′ is changed into an oxide layer which serves as theinsulating layer 33.

Next, in the same vacuum chamber in which the insulating layer 34 isdeposited, the resulting product is dry etched by sputter etching, ionbeam etching, or the like for cleaning the surface thereof. In the thirdembodiment, the previously deposited deterioration reducing layer 33′ isset to have a relatively small thickness in consideration of theconditions for this dry etching, such that the insulating layer 33 isremoved after the dry etching (FIGS. 14A and 14B). Therefore, in thethird embodiment, this dry etching additionally acts as the step ofremoving the deterioration reducing layer 33′ (strictly speaking, theinsulating layer 33 resulting from the oxidization of the deteriorationreducing layer 33′). It should be noted that in FIGS. 14A and 14B, theresist mask for the first lift-off is omitted in the illustration.

Next, the insulating layer 34 is formed in the region removed by thefirst ion milling, with the resist mask for the first lift-off beingleft as it is, and the magnetic domain control layer 32 is furtherformed on the insulating layer 34. Subsequently, the resist mask for thefirst lift-off is removed to complete the lift-off for the layers 34, 32(FIGS. 15A and 15B).

Next, the lower metal layer 23, pin layer 24, pinned layer 25, tunnelbarrier layer 26, free layer 27, upper metal layer 28, oxide film (notshown) on the upper metal layer 28 as mentioned above (not shown),insulating layer 34, and magnetic domain control layer 32 are partiallyremoved by second ion milling using a resist mask (not shown) for secondlift-off for patterning while leaving a strip portion which has anecessary width (width in the Y-axis direction) with respect to theheight direction of the TMR device 2 and extends in the Z-axis directionby a predetermined length. Subsequently, in a region removed by thesecond ion milling, a deterioration reducing layer 35′ is formed whileleaving the resist mask for the second lift-off as it is (FIGS. 16A and16B). It should be noted that in FIGS. 16A and 16B, the resist mask forthe second lift-off is omitted in the illustration.

From the second ion milling to this stage, the foregoing process isperformed within the same vacuum chamber, so that the substrate 101 willnever be placed in the atmosphere.

Subsequently, the substrate 101 having the deterioration reducing layer35′ deposited thereon is placed in the atmosphere to naturally oxidizethe deterioration reducing layer 35′. As a result, the deteriorationreducing layer 35′ is changed into an oxide layer which serves as theinsulating layer 35.

Next, in the same vacuum chamber in which the insulating layer 30 isdeposited, the resulting product is dry etched by sputter etching, ionbeam etching, or the like for cleaning the surface thereof. In the thirdembodiment, the previously deposited deterioration reducing layer 35′ isset to have a relatively small thickness in consideration of theconditions for this dry etching, such that the insulating layer 35 isremoved after the dry etching (FIGS. 17A and 17B). Therefore, in thethird embodiment, this dry etching additionally acts as the step ofremoving the deterioration reducing layer 35′ (strictly speaking, theinsulating layer 35 resulting from the oxidization of the deteriorationreducing layer 35′). It should be noted that in FIGS. 17A and 177B, theresist mask for the first lift-off is omitted in the illustration.

Next, the insulating layer 30 is formed in the region removed by thesecond ion milling with the resist mask for the second lift-off beingleft as it is. Subsequently, the resist mask for the second lift-off isremoved to complete the lift-off for the layer 30 (FIGS. 18A and 19B).

Subsequently, in the same vacuum chamber in which the upper metal layer29 is formed, the resulting product is dry etched by sputter etching,ion beam etching, or the like to remove the oxide film formed on the topof the upper metal layer 28.

Next, the upper metal layer 29 is formed by a sputtering method or thelike, and the upper electrode 31 is formed by a plating method or thelike (FIGS. 19A and 19B).

Finally, the gap layer 38, coil layer 37, insulating layer 39, uppermagnetic layer 36, and protection layer 40 are formed, and theelectrodes 5 a-5 d are formed. Also, the resulting product is annealedfor curing the insulating layer (thermosetting photoresist) 39. By now,the wafer process is completed.

Next, magnetic heads are completed through a known process for the waferwhich has undergone the wafer process. Briefly describing, each bar(bar-shaped magnetic head aggregate) having a plurality of magneticheads arranged in a line on the base is sawed from the wafer. Next, thebar is lapped on its ABS side for setting a throat height, an MR height,and the like for the bar. Next, a protection film 4 is formed on thesurface of the ABS side, and rails 11, 12 are formed by etching or thelike. Finally, the bar is cut by machining into individual magneticheads. In this manner, magnetic heads are completed.

The magnetic head manufactured by the manufacturing method according tothe third embodiment is illustrated in FIGS. 20 to 23. FIG. 20 is anenlarged cross-sectional view schematically illustrating a portion ofthe TMR device 2 and inductive magnetic transducing device 3 in themagnetic head manufactured by the manufacturing method according to thethird embodiment of the present invention. FIG. 21 is a generalsectional view taken along a line B-B′ indicated by arrows in FIG. 20.FIG. 22 is a further enlarged view around the TMR device 2 in FIG. 20.FIG. 23 is a further enlarged view around the TMR device 2 in FIG. 21.FIGS. 20 to 23 correspond to FIGS. 2 to 5, respectively.

It can be understood from a comparison of FIGS. 20 to 23 with FIGS. 2 to5 that the insulating layer 33 resulting from the oxidization of thedeterioration reducing layer 33′ and the insulating layer 35 resultingfrom the oxidization of the deterioration reducing layer 35′ in FIGS. 2to 5 are removed in the magnetic head manufactured by the manufacturingmethod according to the third embodiment.

It has been confirmed in an experiment, later described, that themagnetic head illustrated in FIGS. 2 to 5, manufactured by themanufacturing method according to the third embodiment, can reduce thedeterioration in the characteristics of the TMR device 2 (increasedresistance and reduced MR ratio) due to annealing.

It is thought that the foregoing benefit results from the deteriorationreducing layers 33′, 35′ which have the nature of absorbing and trappingoxygen.

Specifically, oxygen sticking on the end faces of the layers 23-28,exposed by the first ion milling, are trapped by the deteriorationreducing layer 33′, and removed together with the deterioration reducinglayer 33′. Also, oxygen sticking on the end faces of the layers 23-28,exposed by the second ion milling, are trapped by the deteriorationreducing layer 35′, and removed together with the deterioration reducinglayer 35′. It is therefore thought that it is possible to reduce thedeterioration in the characteristics of the TMR device 2 (increasedresistance and reduced MR ratio) due to the annealing.

In the present invention, the manufacturing method according to thethird embodiment may be modified as described below. Also, similarmodifications made to the manufacturing method according to the secondembodiment may be applied to the third embodiment. Further, thesemodifications can be combined as appropriate for application to themanufacturing method according to the third embodiment.

First, the deterioration reducing layers 33′, 35′ may not be oxidized.

Second, only one of the deterioration reducing layers 33′, 35′ may bedeposited in a relatively large thickness, such that the insulatinglayer resulting from the oxidization of the deterioration reducing layerdeposited in a relatively large thickness remains.

Next, description will be made on a method of manufacturing a magnetichead according to a fourth embodiment of the present invention.

The fourth embodiment differs from the aforementioned third embodimentonly in the following aspects, and the magnetic head manufactured by themanufacturing method according to the fourth embodiment is identical tothe magnetic head manufactured by the manufacturing method according tothe third embodiment from a viewpoint of structure.

As described above, oxidizable layers are used for the deteriorationreducing layers 33′, 35′ in the third embodiment. In the fourthembodiment, on the other hand, substantially oxidation-free layers madeof a metal or semiconductor are used instead of the oxidizable layersfor the deterioration reducing layers 33′, 35′. Specifically, each ofthe deterioration reducing layers 33′, 35′ may be formed of asingle-layer film or a composite-layer film made of one or morematerials, for example, selected from the group consisting of Ru, Rh,Pd, Ag, Re, Os, Ir, Pt, and Au.

The fourth embodiment is similar to the third embodiment in that thedeterioration reducing layer 33′ is deposited in a relatively smallthickness, such that the insulating layer 33 is removed after the dryetching for cleaning the surface before the deposition of the insulatinglayer 34, and that the deterioration reducing layer 35′ is deposited ina relatively small thickness, such that the insulating layer 35 isremoved after the dry etching for cleaning the surface before thedeposition of the insulating layer 30.

While the fourth embodiment is similar to the third embodiment in thatthe substrate 101 is placed in the atmosphere after the deposition ofthe deterioration reducing layer 33′, the deterioration reducing layer33′ is not oxidized in the method of the fourth embodiment.Subsequently, the deterioration reducing layer 33′ is removed by dryetching for cleaning the surface, as in the third embodiment, such assputter etching, ion beam etching or the like, in the same vacuumchamber in which the insulating layer 34 is deposited.

Also, while the fourth embodiment is similar to the third embodiment inthat the substrate 101 is placed in the atmosphere after the depositionof the deterioration reducing layer 35′, the deterioration reducinglayer 35′ is not oxidized in the fourth embodiment. Subsequently, thedeterioration reducing layer 35′ is removed by dry etching for cleaningthe surface, as in the third embodiment, such as sputter etching, ionbeam etching or the like, in the same vacuum chamber in which theinsulating layer 30 is deposited.

Except for the aspects mentioned above, the fourth embodiment isidentical to the third embodiment.

As mentioned above, unlike the third embodiment, the deteriorationreducing layers 33′, 35′ in the fourth embodiment are formed of amaterial which is free from oxidization. For this reason, thedeterioration reducing layers 33′, 35′ in the fourth embodiment do nothave the nature of absorbing and trapping oxygen. Instead, thedeterioration reducing layers 33′, 35′ in the fourth embodiment do havea barrier-like nature to oxygen and the like. Therefore, according tothe fourth embodiment, even if the substrate 101 is placed in theatmosphere after the deposition of the deterioration reducing layer 33′,the end faces of the layers 23-28, exposed by the first ion milling, areprotected by the barrier-like nature of the deterioration reducing layer33′, so that oxygen molecules, moisture and the like in the air areprevented from sticking onto the end faces of the layers 23-28. Also,according to the fourth embodiment, even if the substrate 101 is placedin the atmosphere after the deposition of the deterioration reducinglayer 35′, the end faces of the layers 23-28, exposed by the second ionmilling, are protected by the barrier-like nature of the deteriorationreducing layer 35′, so that oxygen molecules, moisture, and the like inthe air are prevented from sticking onto the end faces of the layers23-28.

Consequently, the magnetic head manufactured by the manufacturing methodaccording to the fourth embodiment can also reduce the deterioration inthe characteristics of the TMR device 2 due to the annealing.Nevertheless, the deterioration reducing layers 33′, 35′ are preferablyformed of oxidizable layers as in the third embodiment because theresulting magnetic head can further reduce the deterioration in thecharacteristics of the TMR device 2 due to annealing.

In the present invention, the manufacturing method according to thefourth embodiment may be modified in the following manner. Specifically,one of the deterioration reducing layers 33′, 35′ may be formed of anoxidizable layer. Alternatively, one of the deterioration reducinglayers 33′, 35′ may be formed of a composite-layer film composed of anoxidizable layer and an oxidation-free layer, while the other may beformed of an oxidizable layer or an oxidization-free layer.

Now, a magnetic disk apparatus according to a fifth embodiment of thepresent invention will be described with reference to FIG. 24.

FIG. 24 is a perspective view generally illustrating the configurationof a main portion of a magnetic disk apparatus according to a fifthembodiment of the present invention.

The magnetic disk apparatus according to the fifth embodiment comprisesmagnetic disks 71 rotatably mounted about a shaft 70; magnetic heads 72each for recording and reproducing information to or from associated oneof the magnetic disks 71; and an assembly carriage device 73 forpositioning the magnetic head 72 on a track of the magnetic disk 71.

The assembly carriage device 73 mainly comprises a carriage 75 mountedfor pivotal movements about a shaft 74; and an actuator 76 comprised,for example, of a voice coil motor (VCM) for rotating the carriage 75.

The carriage 75 is mounted with bases of a plurality of driving arms 77which are stacked in the direction of the shaft 74. A head suspensionassembly 78 is secured at the leading end of each driving arm 77. Eachhead suspension assembly 78 has the magnetic head 72 mounted on theleading end thereof. Each head suspension assembly 78 is attached to theleading end of the driving arm 77 such that the associated magnetic head72 opposes the surface of the associated magnetic disk 71.

In the fifth embodiment, the magnetic disk apparatus comprises either ofthe magnetic heads according to the first embodiment, or the magnetichead manufactured by the manufacturing method according to the second orthird embodiment. Therefore, the magnetic disk apparatus according tothe fifth embodiment can advantageously increase the recording density.

A sample magnetic head 1 was manufactured in the same steps as those inthe manufacturing method according to the second and third embodimentsexcept that the deterioration reducing layers 33′, 35′ were not formed.Also, sample magnetic heads 2-10 were manufactured in the same steps asthose in the manufacturing method according to the second and thirdembodiments. In this event, when the sample 1 was manufactured, thedeterioration reducing layers 33′, 35′ were not formed. On the otherhand, when the samples 2-10 were manufactured, the deteriorationreducing layers 33′, 35′ were changed in material and film thickness asshown in Table 2 below, with the remaining conditions being identicalfor the samples 1-10. The compositions of the main layers in the samples1-10 are as shown in Table 1 below.

TABLE 1 Composition and Thickness of Layer (When composed of two layersor more, a layer more to Name of Layer and Reference the left ispositioned lower Numeral in Drawings (near the substrate)) UpperElectrode 31 (serving also NiFe(2□m) as Upper Magnetic Shield) UpperMetal Layer 29 Ta(5 nm) Insulating Layer 30 Al₂O₃(60 nm) Magnetic DomainControl Layer 32 CrTi(5 nm)/CoCrPt(30 nm)/Ta (5 nm) Insulating Layer 34Al₂O₃(5 nm) Deterioration Reducing Layers As shown in Table 2 33′. 35′Upper Metal Layer 28 (Cap Layer) Ta(18 nm) Free Layer 27 CoFe(2nm)/NiFe(3 nm) Tunnel Barrier Layer 26 Al₂O₃(0.6 nm) Pinned Layer 25CoFe(2 nm)/Ru(0.8 nm)/CoFe (3 nm) Pin layer 24 PtMn(15 nm) Lower MetalLayer 23 NiFe(2 nm) Lower Metal Layer 22 Ta(5 nm) Lower Electrode 21(serving also NiFe(2□m) as Lower Magnetic Shield)

TABLE 2 Material and Thickness of Deterioration Reducing Layers 33′, 35′Sample 1 non Sample 2 Ta(0.5 nm) Sample 3 Ta(1.0 nm) Sample 4 Ta(2.0 nm)Sample 5 Al(0.5 nm) Sample 6 Al(1.0 nm) Sample 7 Al(2.0 nm) Sample 8Ti(0.5 nm) Sample 9 Ti(1.0 nm) Sample 10 Ti(2.0 nm)

During the manufacturing of the samples 2-10, sputter etching wasperformed under the following conditions as the dry etching immediatelybefore the deposition of the insulating layer 34 (i.e., the dry etchingfor the insulating layer 33 resulting from the oxidization of thedeterioration reducing layer 33′), and the dry etching immediatelybefore the deposition of the insulating layer 30 (i.e., the dry etchingfor the insulating layer 35 resulting from the oxidization of thedeterioration reducing layer 35′). In the condition, the power was setto 150 W; the flow of Ar gas to 40 sccm; the Ar gas pressure to 7×10−2Pa; and an etching time to 30 seconds.

From a comparison of the etching amount for the insulating layers 33, 35of the respective samples 2-10 under the condition with the thicknessesof the insulating layers 33, 35, it is estimated that no insulatinglayers 33, 35 remain in the samples 2, 5, 8 which have the deteriorationreducing layers 33′, 35′ of 0.5 nm thick, as illustrated in FIGS. 20 to23; it is unknown whether or not the insulating layers 33, 35 remain inthe samples 3, 5, 9 which have the deterioration reducing layers 33′,35′ of 1,0 nm thick; and it is estimated that the insulating layers 33,35 do remain in the samples 4, 7, 10 which have the deteriorationreducing layers 33′, 35′ of 2.0 nm thick, as illustrated in FIGS. 2 to5.

Also, during the manufacturing of the samples 1-10, the samples wereannealed at 250° C. for two hours for curing the insulating layer(thermosetting photoresist) 39.

Then, the resistance and MR ratio of previously fabricated TMR devices 2in the samples 1-10 were measured before and after the annealing,respectively. The result of the measurement is shown in Table 3 below.

TABLE 3 Before After Annealing Annealing Shift Shift MR MR Ratio ofRatio of Resistance Ratio Resistance Ratio Resistance MR ratio (Ω) (%)(Ω) (%) (%) (%) Sample 1 14.2 19.4 21.3 17.6 49.8 −9.5 Sample 2 13.619.0 16.7 17.9 22.6 −5.7 Sample 3 13.6 19.0 14.7 18.2 7.7 −4.1 Sample 410.3 12.8 10.9 13.3 6.1 4.0 Sample 5 13.8 18.8 18.1 17.5 31.1 −6.9Sample 6 12.9 18.4 14.9 17.8 15.1 −3.2 Sample 7 13.5 18.1 13.7 17.7 0.9−2.4 Sample 8 14.1 19.3 19.4 17.9 37.7 −7.3 Sample 9 13.8 19.0 16.2 18.217.7 −4.0 Sample 10 13.7 19.2 15.1 18.8 10.2 −2.3

For each of the samples 1-10, a shift ratio of the resistance and ashift ratio of the MR ratio were calculated from the measuredresistances and MR ratios before and after the annealing. These shiftratios are also included in Table 3. In addition, FIG. 25 shows a graphrepresenting the shift ratio of the resistances for the samples 1-10,and FIG. 26 shows a graph representing the shift ratio of the MR ratiofor the samples 1-10. The shift ratio was calculated in accordance withthe following equation:Shift Ratio={(Value after Annealing−Value before Annealing)/Value beforeAnnealing}×100[%]

As can be seen from Table 3 and FIGS. 25, 26, the samples 2-10, exceptfor the sample 1 which does not include the deterioration reducinglayers 33′, 35′, exhibit the shift ratio of the resistance and the shiftratio of the MR ratio, the absolute values of which are closer to zero,as compared with the sample 1. In other words, it is understood that theuse of a Ta, Al or Ti layer of approximately 0.5 nm-2.0 nm thick as thedeterioration reducing layers 33′, 35′ can limit an increase in theresistance of the TMR device 2 and a reduction in the MR ratio.

It should be understood that the thickness of an oxide film should varydepending on the type of material, so that the thickness is not limitedin the range of 0.5 nm to 2.0 nm. For example, the thickness may be morethan 2.0 nm if the deterioration reducing layers 33′, 35′ are formed ofa metal which is deeply oxidized.

While several embodiments of the present invention and modificationsthereto as well as examples have been described above, the presentinvention is not limited to those.

For example, while the foregoing embodiments have shown examples inwhich the present invention is applied to a TMR device, the presentinvention can be applied as well to a magneto-resistive device which hasa CPP structure such as CPP-GMR.

Also, while the foregoing embodiments have shown examples in which thepresent invention is applied to a magnetic head that employs amagneto-resistive device, the present invention can be applied as wellto a device having a structure in which an insulating layer is incontact with the periphery of a magneto-resistive layer, for example,MRAM, magnetic detector, and the like.

As described above, the present invention can provide amagneto-resistive device which can reduce the deterioration in thedevice characteristics due to annealing, and a method of manufacturingthe same, as well as a magnetic head, a head suspension assembly, and amagnetic disk apparatus which use the magneto-resistive device.

1. A method of manufacturing a magneto-resistive device comprising thesteps of: depositing constituent layers making up a magneto-resistivelayer on a base; patterning one or more layers of said constituentlayers; depositing an oxidizable layer having electric conductivity in aregion in which said one or more layers of said constituent layers havebeen removed by the patterning; oxidizing said oxidizable layer to bechanged into an oxide layer which serves as an insulating layer; anddepositing an insulating layer on said oxide layer so that substantiallyall of a surface of the insulating layer on a side closer to the oxidelayer contacts directly with the oxide layer.
 2. A method ofmanufacturing a magneto-resistive device according to claim 1, wherein:said step of oxidizing includes the step of placing said base in theatmosphere to naturally oxidize said oxidizable layer.
 3. A method ofmanufacturing a magneto-resistive device according to claim 1, furthercomprising the step of performing dry etching for cleaning the surfaceof said oxide layer immediately before said step of depositing saidinsulating layer.
 4. A method of manufacturing a magneto-resistivedevice according to claim 3, wherein said step of performing dry etchingincludes the step of performing the dry etching in the same vacuumchamber in which said step of depositing said insulating layer isperformed.
 5. A method of manufacturing a magneto-resistive deviceaccording to claim 3, wherein said oxide layer substantially remainsafter said step of performing dry etching and after said step ofdepositing said insulating layer.
 6. A method of manufacturing amagneto-resistive device according to claim 1, wherein said oxidizablelayer is formed of a single-layer film or a composite-layer film made ofone or more materials selected from a group consisting of Al, Si, Ti, V,Cr, Mn, Fe, Ni, Co, Cu, Zn, Zr, Nb, Mo, Hf, Ta, and W.
 7. A method ofmanufacturing a magneto-resistive device according to claim 1, whereinsaid magneto-resistive device includes an effective region effectivelyinvolved in detection of magnetism in said magneto-resistive layer, saideffective region being a region in which a current flows in a directionsubstantially perpendicular to the film surface in saidmagneto-resistive layer.
 8. A method of manufacturing amagneto-resistive device according to claim 1, wherein saidmagneto-resistive layer includes a tunnel barrier layer formed on onesurface side of a free layer, a pinned layer formed on one surface sideof said tunnel barrier layer opposite to said free layer, and a pinninglayer formed on one surface side of said pinned layer opposite to saidtunnel barrier layer.